1. Field of Inventions
The present inventions relate generally to valve seats, valves, valved fluid transfer devices and ambulatory infusion devices including the same.
2. Description of the Related Art
Ambulatory infusion devices, such as implantable infusion devices and externally carried infusion devices, have been used to provide a patient with a medication or other substance (collectively “infusible substance”) and frequently include a reservoir and a fluid transfer device. The reservoir is used to store the infusible substance and is coupled to the fluid transfer device which is, in turn, connected to an outlet port. A catheter, which has at least one outlet at the target body region, may be connected to the outlet port. As such, infusible substance in the reservoir may be transferred from the reservoir to the target body region by way of the fluid transfer device and catheter.
The fluid transfer devices in ambulatory infusion devices frequently include a pump, such as an electromagnet pump, and one or more valves. The present inventors have determined that the valves employed in such fluid transfer devices are susceptible to improvement. For example, the present inventors have determined that the main check valves are susceptible to improvement. Main check valves typically include a valve seat and a valve element that is movable relative to the valve seat. The valve element moves between a closed position where the valve element engages and compresses the valve seat, and an open position where the valve element is spaced from the valve seat. The present inventors have determined that adhesion of the valve element to the valve seat, including an increase in adhesion over time in normally closed valves, can reduce the effectiveness of the fluid transfer device by increasing the threshold force required to open the valve. Increasing the threshold force required to open the valve will, in turn, increase the load on the battery and may reduce the amount of fluid that flows through the valve during each pump cycle. The adhesion may also reduce the life of the valve seat itself. The present inventors have also determined that adhesion, including an increase in adhesion over time in normally closed valves, can reduce the effectiveness of other types of valves that may be associated with implantable infusion devices (e.g. bypass valves, outlet valves, pressure regulator valves, fill port valves, valves that employ a reference pressure, header assembly valves, and valves that are associated with catheters).